Tempered glass and process for manufacture of the same



.June 1o, 1941; Lon@ 2,244,115

TEMPBRED GLASS AND PROCESS FOR IANUFAGTURE OF THE SAIE Filed Dec. 17, 1955 3 Sheets-Sheet 1 B.' ,LONG

June 10, 19.41.,v

TEMPERED GLASS AND PROCESS FOR MANUFACTURE 0F I.IHE SAME .Filed Dec. 17, 1935 3 Sheets-Sheet 2 j, @Milo @zum www?

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SMM/MA; S

June 10, 1941.

B.) LoNG 2,244,

T EMPERED GpAssANn PaocEss Fommuumcrun oF THE 'SAME Filed Dec. 17. A1955 3 Sheets-She VN-ll-Wl-IC.

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LJ'ULJU Ummm-DE @EDU551 V1 V1 FIJ-TV Patented June l0, 1941 UNITI-:D VSTATES PATEN OFFICE' 2,244,715 t 'ram-Enno GLASS AND r ss Foa MANUFACTUBE or 'r saam.

Bernard Inng,`1"arls, France, assignor to The American Securlt Company, Wilmington, Del.,

a company of Delaware Application December m, 1935, serial No. 54,918

In France December 22, 1934 i ,1a claims. (ci. 449-89) When tempered glass is used for windows, partimmy in wind-shields or automobiles, a breaks' under the inuence of a shocki into a large num- -ber of small harmless fragments, its transparency is altered at the time that the-fragmentation is produced; when the fragments remain attheir lplace wi-thin the wind-shield a new accommodation of the eye is necessary for the visibility again to become satisfactory. this accommodation, though very short, in the meanwhile may perhaps be suilicient, in the case of high speeds of the-vehicle, to cause a disturbance in'its` driving, resulting in accidents.

The present invention remedies this objection. It has for its object a ,new industrial product.

formed by'a tempered sheet of glass or a temof the presence of the pieces of larger dimensions the visibility remains sufllcient at the time of the zones, and then to cool .it suddenly and in a uniform manner over its entire surface, or to' .The duration of `the first-mentioned zones so that the.-

break. By adopting sufllciently reduced dimensions for each of the said second-mentioned zones and giving to their periphery aproper shape the pieces coming from these zones in. case of breakage arey not dangerous while Vkeeping suillcient visibility. The encompassing or encircling zones with ne fragmentation have for' example a size of 10 to 15 mm., the encompassed zones, more or less rounded and formed by a single piecey or by a small number of pieces, having a diameter of 4from 50 to 70 mm.

The invention concerns, furthermore, a process for the fabrication of this product which conslats in subjecting the two types of zones to different thermal conditions in a manner to produce al stronger tempering in the encompassing or surrounding zones, which'assures in the case of breakage a ilne fragmentation thereof, the end or surrounded zones being tempered less and not breaking or breaking up into larger pieces Flnally, the invention comprehends modes of 50.

realizing the process which consists, for example, either to heat uniformly the sheet of glass Y ver'its entire surface and then to cool it more strongly in the encompassing or encircling zones,

or to heat it more strongly in the encirclingA effect a variation of the intensity of the heating and cooling in the same sense in such a manner that these intensities are stronger in the encircling zones, or to reheat the sheet in the encircled zones after -it has undergone a tempering by `a generalv heat followed by a uniform cooling, in a manner to diminish the degree of tempering of these zones. f

In the annexed drawings",

Figs. 1 and 2 represent, asI eilcamples, two views of the fragmentation of glass tempered in acoordance with the invention;

Fig. 3 is a vertical section of an arrangement for cooling by blowing localized upon-thev encompassing zones;

Fig. 4 is a front view of this arrangement Fig. 5 relates to a variation 'of the arrangement of Figs. 3 and 4; V

Fig. 6 is a verticalsection of a heating arrangement localized upon thev encompassing l zones; A v Fig. 'I is a front view of a portion of the arrangement of Fig. 6;

Fig. 8 is a sectional view of an arrangement for the re-heating of the encompassed zones after the tempering of the sheet of glass;

Figs. 9 and 10 are front views of this arrangement.

In Figures l and 2, the encompassing or surrounding zones a of fine .fragmentation are indicated by hatching,.while the encompassed or surrounded zones b wherethe fragmentationis nil,

or greatly reduced, are-not hatched.

The ilrst manner of realizing the process represented in Figures 3 and 4 consists in, after having heated -the sheet of glass c in a uniform manner by known means, cooling it more strongly in the encircling zones.

For this purpose, \the tempering Japparatus comprises two networks lof blowing tubes l disposed on the opposite sides of the sheet and pierced by holes 2 through which av cooling uld I is projected upon the zones of ilne fragmentation which are to be produced in, the sheet.

` The blowing holes have a small diameter, for example 2 to -3 mm. andare very close to each other. The distance between the outlet of the iets and the surface 'of the glass must be slight,

without nevertheless being .such that the jets -produce impressions in the glass; 2 to 3 cm. havev been found sufficient in practice. l

` 1n order to shield the portions of the glass' of the surrounded zones from a too suddencooiing, l I

a uniform cooling.

the screens 4 are disposed in each of the spaces between the meshes of the blowing network. The

. distance from these screens to the sheet of glass is adjustable, independently of the distance from the blowing holes to the sheet, by means of the rods 5 which support the screens and which slide in the guides 6. By this adjustment eitherall contact of blowing air with the surrounded zones may be excluded in ah absolute manner or a portion thereof may be permitted to4 act in said zones, in the ferm of eddies. Thus the degree of tempering desired to be imparted to the surrounded zones can be adjusted exactly. The two networks of tubes I rest through the intermediary of the inlet casings 1 upon the movable .plates 8 upon which are xed likewise the frames 9 carrying the screens 4. By means of the cranks I0, the whole assembly of tubes and screens can be shifted aside simultaneously in order to introduce the sheet of glass and thereafter brought edges of the sheet and its center, a small section I is imparted-to the rods 5 and the frames 9 are removed sufficiently from the blowing grilles by giving, for this purpose, a sufficient length to the rods 5.

The distance from the screens 4 to the sheet alsomay be modified individually so that their.

tween the edges and thecenter of this sheet.

In the variation of this device represented by Fig. 5, in which the same numerals designate the same elements as in Figs. 3. and 4, the air which has served for cooling' the sheet c does not escape freely but is sucked in by a casing 1 II', in which a suitable under-pressure is attained by means of a ventilator or by any other means. 'Y

A second mode of realizing the process consists in heating the sheet more strongly in the encompassing or surrounding zones, then cooling it suddenly by means of known apparatus with For this purpose, .the heating arrangement comprises (Figs. 6, 7) two networks of heating resistances, disposed upon the opposite sides of the sheet ofl glass and formed by conductors i2 fixed in refractory frames or braces I 3, which, viewed normally to the plate glass, affect the form'ofgthe paths of ne' fragmentation Yor enoompassing zones which are contemplated to be occasioned in .the sheet. The conductors I24 are placed a slight distance from the sheet, which localize the heatin the zones of the glass which are situated in front of the frames I3 of 4the networks. 'In the meshes thereof are disposed the screens I4, by virtue of which th gloompassed zones are shielded from the radiation ofl conductors .I2. .These screens are hollow and may be traversed bye. cooling iiuid. Their distances to the sheet of glass, moreover, can be adjusted independently of the heating frame I3? and independently of each other.

Figs. v8, 9 and l0 relate A.to a third mode of vaction can be rendered different, for example be- The heating elements AI5 are mounted' upon two plates I6 of refractory material disposed upon the opposite sides of the sheet c at the lo#- cations corresponding 'to the encompassed or surrounded zones which are contemplated to 'be occasioned therein. Between the different heating regionsI I5 of each plate are interconnected the bars of a grille I1 represented in part in Fig. 10 of which the outline corresponds to the encompasslng or surrounding zones. These bars maysbe' hollow and traversed by a cooling fluid. Thev sheet of glass is placed in contact with the grilles, which protect'it in the encompassing orV surrounding zones against the action of the heating elements I5.

In order that a sheet of glass fall within the limits of the invention, it is not necessary that it presents upon its whole surface the type of break which has served to characterize the invention, but it is sufilcient that it presents this mode of fragmentation upon a part of its surface. So it is, that in a wind-shield, the invention can be limited' to the portion of glass which finds itself inl front of the drivers eyes. 'I'he different proc- Y 5 esses of fabrication will be regulated, in consequence, in a Imanner that the state of the indicated tempering is caused onlyin the corresponding parts of vkthe sheet.

It is apparent likewise that the different processs which have been described can be combined, l

for example, by adding heat more strongly upon the encompassing zones to the stronger cooling upon these same zones, or to combine one of these two means with reheating effected after tempering upon the encompassed zones.

The apparatus herein shown is claimed inv myapplication Serial N0. 262,578, led March 17,

- `1939, as a division hereof.

realizing the vprocess in which the sheet of glass. after having been tempered by. a heating and I a sudden uniform cooling,'is reheated anew in Having thus described my invention what I claim as new and desire to secure by U. 8. Letters Patent is: v

1. A new article of manufacture comprising a sheet of glass having at least a portion thereof tempered in order to produce zones of dierent degrees of tempering, each of the less tempered zones being entirely surrounded lby a higher tempered zone.

2. As a new article of manufacture a tempered sheet of glass comprising zones giving by break.-

age numerous small fragments which surround entirely zones wherethe fragments in case of breakage arev of larger'dimehsions.

3. As a new article of manufacture a tempered sheet of glass which, when broken, produce fragments of comparatively large size, each fragment being entirely surrounded by numerous fragments of very small dimensions.

4. As a new article of manufacture a sheet of glasshaving tempered zones surrounded by other zones which are tempered toa higher degree\than the first-mentioned zones whereby,if the sheet is broken, the surrounding` zonesA give numerous small fragments and the surrounded zones give J polygonal and rounded forms, so that by virtue of the presence of these pieces of large dimensions, the of the sheet after receiving `the shock is not diminished unduly.

6. As a new article of manufacture a sheet of glass having tempered zones surrounded by other zones which are tempered to a higher degree than the first-mentioned zones whereby, if the sheet is broken. the surrounding zones give numerous small fragments .and the surrounded zones give pieces having larger dimensions, the dimensions of the surroimded zones being such that the pieces coming from said zones cannot be dangerous if they are projected.

la lesser degree than vsaid first mentioned zones which comprises subjecting the two types of zones to different thermal treatments to produce a high temper in the first named zones.

9. A method of manufacturing a sheet of glass having in at least a portion thereof tempered zones surrounding sones which are tempered to a lesser degree than said ilrst mentioned zones which comprises heating said portion of the sheet uniformly over its whole surface and cooling said portion more strongly at said first mentioned zones.

v10. A method of manufacturing sheet glass having in at least a portion thereof tempered zones surrounding zones which are tempered to a lesser degree than said first mentionedgzones which comprises heating said portion of the sheet more intensely at said first mentioned zones and. Y cooling the sheet suddenly and uniformly over its whole surface.

l1. A method of manufacturing a sheetof glass having in. at least a portion thereof tempered zones surrounding zones whichare tempered to a lesser degree than said ilrst mentioned zones which. comprises heating said portion of the sheetv and at least cooling said portion more intensely at said first mentioned zones.

i2. A method of manufacturing a sheet of glass having in at least a portion thereof tempered zones surrounding zones which are tempered toa lesserdegree than said first mentioned zones -which comprisesheating more intensely and cooling more intensely said portion of the sheet at said ilrst mentioned wnes.

13. A sheet of glazing glass having therein areas of substantial size devoid of acute corners and free of high temper and separated from each other by areas of high temper.

yBERNARD LONG. 

